红外与激光工程
2024, 53(1): 20230372
Author Affiliations
Abstract
1 Department of Mechanical Engineering, Iowa State University, Ames, IA 50011, United States of America
2 School of Mechanical and Automotive Engineering, Shanghai University of Engineering Science, 333 Longteng Road, Shanghai 201620, People’s Republic of China
3 College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, Guangdong 518055, People’s Republic of China
Raman spectroscopy-based temperature sensing usually tracks the change of Raman wavenumber, linewidth and intensity, and has found very broad applications in characterizing the energy and charge transport in nanomaterials over the last decade. The temperature coefficients of these Raman properties are highly material-dependent, and are subjected to local optical scattering influence. As a result, Raman-based temperature sensing usually suffers quite large uncertainties and has low sensitivity. Here, a novel method based on dual resonance Raman phenomenon is developed to precisely measure the absolute temperature rise of nanomaterial (nm WS2 film in this work) from 170 to 470 K. A 532 nm laser (2.33 eV photon energy) is used to conduct the Raman experiment. Its photon energy is very close to the excitonic transition energy of WS2 at temperatures close to room temperature. A parameter, termed resonance Raman ratio (R3) Ω = IA1g/IE2g is introduced to combine the temperature effects on resonance Raman scattering for the A1g and E2g modes. Ω has a change of more than two orders of magnitude from 177 to 477 K, and such change is independent of film thickness and local optical scattering. It is shown that when Ω is varied by 1%, the temperature probing sensitivity is 0.42 K and 1.16 K at low and high temperatures, respectively. Based on Ω, the in-plane thermal conductivity (k) of a ～25 nm-thick suspended WS2 film is measured using our energy transport state-resolved Raman (ET-Raman). k is found decreasing from 50.0 to 20.0 Wm-1 K-1 when temperature increases from 170 to 470 K. This agrees with previous experimental and theoretical results and the measurement data using our FET-Raman. The R3 technique provides a very robust and high-sensitivity method for temperature probing of nanomaterials and will have broad applications in nanoscale thermal transport characterization, non-destructive evaluation, and manufacturing monitoring.
resonant Raman scattering two-dimensional (2D) materials Raman intensity ratio ET-Raman thermal conductivity International Journal of Extreme Manufacturing
2022, 4(3): 035201
Author Affiliations
Abstract
1 Institute of First Medical Center, Chinese PLA General Hospital, Beijing 100853, China
2 State Key Laboratory of Solid-State Lighting, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
We report on the effect of inserted photonic crystalline (Ph-C) in the GaN epitaxial layer on the incorporation of the indium component for the InGaN-based green LED. The adoption of Ph-C in the GaN layer shifted the Raman peak value of E2 mode of GaN to lower frequency and resulted in a tensive stress relief. The stress relief can be attributed to strained lattices restoring in the matrix of Ph-C and the GaN pseudo-epitaxy over the air-void of the Ph-C. Moreover, the HRXRD rocking curves and AFM results show that the insertion of Ph-C also improves the crystal quality. With the inserted Ph-C, the indium component in the multiple quantum wells of the green LED (Ph-C LED) was enhanced. This resulted in a 6-nm red-shift of the peak wavelength. Furthermore, the LOP of the Ph-C LED was enhanced by 10.65% under an injection current of 20 mA.We report on the effect of inserted photonic crystalline (Ph-C) in the GaN epitaxial layer on the incorporation of the indium component for the InGaN-based green LED. The adoption of Ph-C in the GaN layer shifted the Raman peak value of E2 mode of GaN to lower frequency and resulted in a tensive stress relief. The stress relief can be attributed to strained lattices restoring in the matrix of Ph-C and the GaN pseudo-epitaxy over the air-void of the Ph-C. Moreover, the HRXRD rocking curves and AFM results show that the insertion of Ph-C also improves the crystal quality. With the inserted Ph-C, the indium component in the multiple quantum wells of the green LED (Ph-C LED) was enhanced. This resulted in a 6-nm red-shift of the peak wavelength. Furthermore, the LOP of the Ph-C LED was enhanced by 10.65% under an injection current of 20 mA.
Journal of Semiconductors
2022, 43(7): 072801
哈尔滨工业大学仪器科学与工程学院, 现代显微仪器研究所, 黑龙江 哈尔滨150080
近年来,荧光显微成像技术由于良好的特异性、高的对比度和信噪比等性能优势,被广泛应用于生物物理学、神经科学、细胞学、分子生物学等生命科学研究的各个领域。然而,传统的荧光显微镜仍然存在分辨率、成像速度、成像视场、光毒性和光漂白等的相互限制,使其在亚细胞结构观测、活体生物超精密成像和分子结构研究领域的应用受到了极大阻碍。由于传统荧光显微镜的局限性,研究人员将目光投向了由数据驱动的深度学习方法。基于深度学习的显微镜的出现,丰富了现有的光学显微成像技术,大数据量的训练突破了传统光学显微镜所能够达到的功能和性能的疆界。本文聚焦基于深度学习的荧光显微成像技术,首先对深度学习的基本原理以及发展过程进行简要概述,随后针对深度学习在荧光显微成像领域近年来的国内外最新成果进行总结,之后通过与传统显微成像系统进行对比,阐述了深度学习在解决荧光显微成像问题上的优越性,最后对深度学习在显微成像技术上的应用前景进行了展望。
显微 深度学习 荧光显微镜 超分辨 光学成像 激光与光电子学进展
2021, 58(18): 1811007
红外与激光工程
2021, 50(6): 20211039
采用水热法在FTO(fluorine-doped tin oxide)基底上制备不同形貌的锐钛矿结构TiO2薄膜。通过不断增大反应前驱物中盐酸浓度, TiO2薄膜由球状颗粒薄膜逐渐演变生长成大面积高能(001)面裸露的TiO2纳米片阵列薄膜。通过对形貌演化规律及X射线衍射图谱变化规律进行分析, 提出了不同形貌TiO2薄膜的生长演化机制, 并对盐酸在其中的作用进行了说明。为了进一步改善TiO2薄膜的性能, 采用连续离子层吸附反应法对不同形貌的TiO2薄膜进行CdS量子点敏化。采用紫外可见吸收光谱分析法和三电极体系对复合薄膜的光吸收性能和光电化学(PEC)性能进行了研究, 实验数据显示CdS/TiO2复合薄膜的光电化学性能皆明显优于单纯TiO2薄膜, 而且纳米片阵列薄膜的性能明显优于其他形貌薄膜, 说明了大面积高能(001)面裸露的TiO2纳米片阵列薄膜的性能优越性。
TiO2薄膜 (001)晶面 晶体生长 水热法 量子点 敏化 TiO2 thin film (001) lattice plane crystal growth hydrothermal method quantum dot sensitization
1 上海工程技术大学机械与汽车工程学院, 上海 201620
2 美国爱荷华州立大学机械工程系, 美国 爱荷华州 50011
3 上海海洋大学工程学院, 上海 201306
4 武汉大学动力与机械学院, 湖北 武汉 430072
激光辅助近场纳米制造是利用近场聚焦激光束突破衍射极限对材料进行加工,使其发生纳米域内的相变或爆炸,从而制造纳米级材料和复杂结构的技术。基于探针的激光辅助近场制造技术是激光辅助近场纳米制造的一大分支。加工域内原位光场、温升、应力以及材料结构演变是纳米加工动态过程中的重要信息,有助于深入理解纳米加工过程多物理场相互作用的物理机制,以及进一步优化加工过程控制。本文主要综述了基于扫描探针显微镜探针针尖的激光辅助近场纳米加工中光场、温度场、应力场探测的实验和结构演变的理论计算工作。
显微 近场显微镜 激光辅助纳米制造 拉曼光谱 分子动力学模拟
